Some useful ideas for multistate protein design: Effect of amino acid substitutions on the multistate proteins stability and the rate of protein structure formation.

The design of new protein variants is usually confined to slightly "fixing" an already existing protein, adapting it to certain conditions or to a new substrate. This is relatively easy to do if the fragment of the protein to be affected, such as the active site of the protein, is known. But what if you need to "fix" the stability of a protein or the rate of its native or intermediate state formation? Having studied a large number of protein mutant forms, we have established the effect of various amino acid substitutions on the energy landscape of the protein. As a result, we have revealed a number of patterns to help researchers identify amino acid residues that determine the folding rate and the stability of globular proteins states and design a mutant form of a protein with desired properties.

[Bacteriophage T5 Mutants Carrying Deletions in tRNA Gene Region].

A new series of heat-stable (st) mutants of bacteriophage T5, which contains deletions in the tRNA gene region, has been isolated. An accurate mapping of the deletion boundaries for more than 30 mutants of phage T5 has been carried out. As a result of the analysis of nucleotide sequences flanking the deleted regions in wild-type phage DNA, it has been shown that they all contain short, direct repeats of different lengths (2-35 nucleotide residues), and that only one repetition is retained in the mutant phage DNA. On the basis of the obtained results, it was suggested that deletion mutants of the phage T5 are formed as a result of illegal recombination occurring with the participation of short repeats in DNA (SHDIR). Based on the example of two mutants, it has been shown that the resistance to thermal inactivation depends on the size of the deleted region.

[A New Simple Technique for Producing Labeled Monoclonal Antibodies for Antibody Pair Screening in Sandwich-ELISA].

A simple and fast method for obtaining biotin-labeled monoclonal antibodies was developed usingcontent of hybridoma culture supernatant sufficient to select antibody pairs in sandwich ELISA. The method consists in chemical biotinylation of antigen-bound antibodies in a well of ELISA plate. Using as an example target Vaccinia virus A27L protein it was shown that the yield of biotinylated reactant is enough to set comprehensive sandwich ELISA for a moderate size panel of up to 25 monoclonal antibodies with an aim to determine candidate pairs. The technique is a cheap and effective solution since it avoids obtaining preparative amounts of antibodies.